1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Rear diff issue?

Discussion in 'Newbie Q & A' started by Btngu2, Aug 13, 2016.

  1. walter

    walter Studio Forums Elite
    ELiTE MEMBER

    Joined:
    Jan 8, 2013
    Messages:
    4,209
    Likes Received:
    2,349
    always turn the truck off first . always turn the transmitter on first.
     
    Monkeypiarat likes this.
  2. Btngu2

    Btngu2 Active Member

    Joined:
    Aug 12, 2016
    Messages:
    94
    Likes Received:
    27
    I usually do, just was frustrated with the servo and axles, I wasn't paying attention.
     
    Monkeypiarat likes this.
  3. Btngu2

    Btngu2 Active Member

    Joined:
    Aug 12, 2016
    Messages:
    94
    Likes Received:
    27
    Anyone interested in a brushed emaxx that needs a servo? Lol
     
    Monkeypiarat likes this.
  4. lout

    lout Studio Forums Elite
    ELiTE MEMBER

    Joined:
    Oct 9, 2012
    Messages:
    3,794
    Media:
    58
    Likes Received:
    2,129
    LMAO ... Yeah the runaway vehicle is normal if you turn the receiver off first.

    Now the thinking is this, for some reason the BEC circuit in the ESC has failed and is putting out the full 8.4 volts. Now it would seem that the receiver can handle it (surprising as they usually only like 6volts) and the that 8.4 volts is being passed directly to the servo.

    It's all I can think of that would explain the death of 4 servo's in the manner which you mention..

    This also assumes that the battery is connected to the ESC and the ESC is connected to the receiver and the servo is connected to the receiver only.

    To test this your going to need a multi meter and check the red/black output of channel 1 on the receiver and see how many volts is being sent to the servo

    Alternatively you could try with just a 2S or 7.2v NiMH 6 cell which has a safe voltage for servo's. Now to be honest I would not be using anything but cheap servo's in this rig until the matter is sorted. HK Has a 440oz waterproof metal geared servo available for under $10
     
    Little Rascle likes this.
  5. darkside0914

    darkside0914 Studio Forums Elite
    ELiTE MEMBER

    Joined:
    Nov 26, 2012
    Messages:
    3,440
    Media:
    44
    Likes Received:
    2,203
    that's actually fairly common, which is why we generally tell you to shut off power to the truck 1st to prevent runaway, and yes check your voltage, most servos i've seen can withstand a max of 7.4v and some can't go over 6v, but this really shouldn't be a problem unless your escs built in bec is malfunctioning or your running the receiver directly off the battery.
     
  6. Monkeypiarat

    Monkeypiarat Worlds formost authority on my own opinion
    ELiTE MEMBER

    Joined:
    Aug 12, 2013
    Messages:
    2,542
    Likes Received:
    1,293
    when you check the red black output of channel 1 on the receiver ...
    something you can try to see if it makes a difference ....
    find the ST-D/R.. adjustment on the transmitter ....
    here is a link so you know what I am talking about....
    http://docs.axialracing.com/instruc...4206-i001_-_AX-3_Transmitter_Instructions.pdf
    while you are checking the red black output of the CH1 on the receiver ...
    adjust the ST-D/R knob and look to see if it changes the output in the CH1...
    if it does make sure before you finish checking that the output is no more that 6.o volts ...
    then take note of the setting,,,
    and do not go above the point where the 6 volt mark is on the adjuster ...
    then when you can put the RC up on a stand so the wheels are off the work surface ..
    and do your channel diagnosis ..with the RC off as well as on and operating
    if you are handy ,,, I would suggest making a diagnostic plug,,,
    with a lead off of one of the fried servos....
    so you can just plug in to the channel you want to test ..
    and just be able to test the red and black wires ....
    while up on the stand to check the voltage output while the servo is also connected ...
    you will need to have the equivalent of....
    a servo extension with pig tails added to the wires between the plugs to test ..
    the channel output while in operation ....
    just keep your channel checking tool/tools you made when you are done ....
    for future use the servo wire extension with the pigtails ,,
    would be the deluxe tool and serve both purposes..
    and the servo plug to check from the wires will only allow you to check with the servo disconnected...
    if you are having a run away ...
    every time you turn off the rc and transmitter in the wrong order ,,,
    rebind the transmitter to the receiver ...
    you should always turn OFF the RC FIRST...
    and turn ON the transmitter FIRST.... for safety reasons ,,,,,
    how ever I don't think that you should have a run away RC every time you do it backwards ...
    rebinding the TX/RX should clear this up and you never know.....
    It might make a difference on the multi meter reading to ..
     
    #66 Monkeypiarat, Oct 15, 2016
    Last edited: Oct 15, 2016
    Little Rascle likes this.
  7. Btngu2

    Btngu2 Active Member

    Joined:
    Aug 12, 2016
    Messages:
    94
    Likes Received:
    27
    OK, I checked the power. It has 7.9 volts, the same as my battery?
     
    Monkeypiarat likes this.
  8. Monkeypiarat

    Monkeypiarat Worlds formost authority on my own opinion
    ELiTE MEMBER

    Joined:
    Aug 12, 2013
    Messages:
    2,542
    Likes Received:
    1,293
    I think that 7.9 volts is a little high ... do you have an other battery to try .....
    or if you can discharge this battery to a lower voltage,,,
    and see if the voltage goes down with the battery when you check it ..
    if it does then I think your power is running straight through from the battery to servo...
    did you try to turn down the ST-D/R.. adjustment on the transmitter....
    you could turn it all the way down and see if that changes the reading...
    you could swap out the ESC from an other RC just to see if it fixes......
     
  9. Btngu2

    Btngu2 Active Member

    Joined:
    Aug 12, 2016
    Messages:
    94
    Likes Received:
    27
    Got another battery and it had 3.3 volts. Check the wire, and it has 3.3 volts. So bad ESC? Only one I have spare is an evx2 that runs on 2 battery packs.
     
    Monkeypiarat likes this.
  10. scalemadness

    scalemadness Studio Forums Elite
    ELiTE MEMBER

    Joined:
    Jan 18, 2014
    Messages:
    907
    Likes Received:
    612
    If the internal bec is done on your esc buy a $25 castle bec disconnect the red wire from the plug that goes from your esc to your rx connect the bec to your esc battery connector and plug it in to a aux or into the bind port on your rx this will save you from buying a new esc
     
    Monkeypiarat and lout like this.
  11. Monkeypiarat

    Monkeypiarat Worlds formost authority on my own opinion
    ELiTE MEMBER

    Joined:
    Aug 12, 2013
    Messages:
    2,542
    Likes Received:
    1,293
    with the evx 2 esc the specs say that the BEC output is 6.0 volts..
    https://traxxas.com/products/parts/otherparts/3019evx2
    however.... it does also say
    Input voltage: 6-14 cells (7.2 to 16.8 volts DC) ....
    so if you wanted you could check it with one 7.2 pack....
    however with our friends input I want to believe that lout is correct ..
    that your internal BEC developed a mind of its own ...
    and the information that scalemadness offered will do the trick ...
    here is my thinking .... with all the checks and balances provided from knowledgable friends ...
    I am confident that you can make an informed decision on what is in your best interest ...
    and I could help you with further because of the information provided ...
    so at this point I think it is time to put the advice in to action?
    I mean I could come up with all kinds of checks and balances....
    because of the info given ... but what would be the point if we feel we have the answer;)
    at this point I believe it is a bad esc ....
    and the temporary fix would be an external BEC ....
    with the knowledge that later in your journey an external BEC very well might be a must any way ...
    should you decide to add more accessories ...
    if you need any more help extracting information ... repost
    or if there is any more help I can offer let me know ....:)
     
  12. drzoo2

    drzoo2 Studio Forums Elite
    ELiTE MEMBER

    Joined:
    Dec 2, 2012
    Messages:
    1,601
    Media:
    1
    Likes Received:
    886

    AR-3/FS-GR3C receivers have a Fail-safe for when they lose connection to the transmitter. Use the little plastic stick that comes with your bind plug. There is a hole to the right of the STR (CH1) channel label. You can see it in the picture below....

    [​IMG]

    Use the the stick or some other small pin to press the button for about 3seconds with the radio and RC powered on, AT REST. The LED should flash and stop when completed. To test, turn off your transmitter with the wheels off the ground.

    Do this after you get your BEC issue fixed. The specification for the receiver is 4.5v - 6.5v

    There is something very wrong somewhere. A crawler should not pull enough current to heat any battery to the point of failure. The BEC inside the AE-5 is pretty weak and is rated to 2amps on 2S (8.4v Charged). It's "just" good enough for the stock servo. Any decent servo will pull more current than it can handle.

    Point is, regardless of whether you need a new ESC, if your going to run stronger servos you really should be using an external BEC.
     
    #72 drzoo2, Oct 16, 2016
    Last edited: Oct 16, 2016
    lout and scalemadness like this.
  13. Btngu2

    Btngu2 Active Member

    Joined:
    Aug 12, 2016
    Messages:
    94
    Likes Received:
    27
    Ordered a new ax5 and a Bec along with a hitec servo. Im not familiar with a Bec. Any tips or notes?
     
  14. Btngu2

    Btngu2 Active Member

    Joined:
    Aug 12, 2016
    Messages:
    94
    Likes Received:
    27
    Also a non related question, the emaxx I have needs 2 servo's and tires. I can trade it for an scx10 that needs a front drive shaft, Rx/tx, and body mounts. Is it worth it?
     
    Monkeypiarat likes this.
  15. Btngu2

    Btngu2 Active Member

    Joined:
    Aug 12, 2016
    Messages:
    94
    Likes Received:
    27
    Just an update and another question. Hate to keep this thread going, but people don't like it when you bump an old thread? So I got my new ESC, servo, and receiver installed. It is extremely smooth. My new question is about suspension. I'm not sure about other crawlers, but mine has a lot of torque twist, even with the recommended setups. I did some looking and found some springs that where the same length as mine, but extremely soft. I put them on, and almost no twist at all. But, I only have about a quarter of an inch before it bottoms out on my shock stops. Since my top speed is extremely slow, I don't think it will hurt anything, but I'm new to all this and wanted to ask the forum. Crawling wise, there is a Huge improvement. It seems that all wheels are on the ground 99% of the time.
     
    lout and Monkeypiarat like this.
  16. Btngu2

    Btngu2 Active Member

    Joined:
    Aug 12, 2016
    Messages:
    94
    Likes Received:
    27
    Can the channel 3 be used for anything? I'm looking to add rear steer
     
    Monkeypiarat likes this.
  17. scalemadness

    scalemadness Studio Forums Elite
    ELiTE MEMBER

    Joined:
    Jan 18, 2014
    Messages:
    907
    Likes Received:
    612
    Using channel 3 depends on your radio and its settings for a third channel like endpoints ect.
     
  18. Btngu2

    Btngu2 Active Member

    Joined:
    Aug 12, 2016
    Messages:
    94
    Likes Received:
    27
    I currently have the ax3
     
    Monkeypiarat likes this.
  19. scalemadness

    scalemadness Studio Forums Elite
    ELiTE MEMBER

    Joined:
    Jan 18, 2014
    Messages:
    907
    Likes Received:
    612
    I dont believe there is any way to control the third channel from that rx/tx set up
     
  20. Monkeypiarat

    Monkeypiarat Worlds formost authority on my own opinion
    ELiTE MEMBER

    Joined:
    Aug 12, 2013
    Messages:
    2,542
    Likes Received:
    1,293
    rear steer can be done with a y connector to the steering channel ,,,
    and running both of the front and rear servos from that...
    but it will only rear steer and make your turning radius smaller ....
    if you want to crab walk you will need to be able to control the third channel ...
    other wise you will only be able to use the uncontrolled third channel as a power supply
    for lights or similar accessory ...
     
    walter likes this.

Share This Page